You haven't played it?
I'll give you the gist of why I think so (in my opinion obviously): You are supposed to improve upon aspects of your previous game in sequels, not remove 3/4 of the features that most people loved. Basically, it is a broken, and unfinished game.
Actually I have played it. I thought It was a pretty good game, although the approach it took was to attract COD players, I say it worked out rather well.
Sure, it wasn't the greatest Killzone (Killzone 2 beats it by a mile), but it did improve in a few key aspects of gameplay.
However, this is not the place to discuss such matters, as the moderators shall come down upon us in mere seconds and we will be noted as spammers..